This is how to mill a straight keyway on a shaft using a BRIDGEPORT MILLING MACHINE. Watch my other video that show how to cut a woodruff (half moon) key seat. And yet another video that shows how to BROACH a keyway in a pulley bore.
https://www.exciteshadesails.com.au/blog/ How to install a shade sail from excite shade sails, featuring the inline turnbuckle for tensioning the perimeter wire.